Colloidal Stabilization by Adsorbed Gelatin

Abstract

The stabilizing effect of adsorbed polyampholyte on colloidal dispersions is quantified through small angle neutron scattering measurements of the structure of concentrated dispersions. Gelatin is adsorbed onto colloidal acrylic latex particles of like net charge to provide both steric and electrostatic stabilization. The extent and structure of the adsorbed gelatin corona is measured using dynamic light scattering (DLS), small angle neutron scattering (SANS) and dilution viscometry (DV). The SANS spectra from concentrated dispersions of bare and gelatin-coated colloidal particles are modeled via integral equation theory using pair potentials that superimpose an electric double layer and a simple model of steric repulsion, where all the parameters are determined a priori. Our results demonstrate for the first time that the stabilizing forces arising from the adsorbed gelatin can be predicted quantitatively from a simple combination of Derjaguin−Landau−Verwey−Overbeek (DLVO) theory and a model for the adsorbed polymer brush. These results agree with previous studies of the surface forces of gelatin adsorbed onto mica cylinders and are important for understanding colloidal stabilization imparted by adsorbed polyampholytes.